Have you ever bitten into an apple, set it down for a few moments, and found that it has turned brown? This results in new chemicals (o-quinones), which then react with amino acids to produce brown-colored melanins. The enzyme then has access to oxygen in the air and it does its thing, turning the fruit brown. The simple science is that when an apple is damaged, even cut into slices, the enzymes in the apple react to the oxygen in the air causing oxidation.The apple produces melanin to protect the apple which is the brown you see. Kitchen Science Why Do Apples Turn Brown? Packaged apples found at McDonalds or in your local produce section are usually treated with a solution of calcium ascorbate (a blend of calcium and vitamin C) or citric acid (found in citrus fruit) to maintain freshness and color. Why Do Apples Turn Brown? This reaction is also called enzymatic browning and is one of the largest causes of spoilage in fruits and vegetables—even though it does not make the food harmful to eat. Brown pears are safe to eat but may not be pleasant. The trigger for this is damage to the cells, such as when you cut the apple, which then results in certain enzymes within the cells being exposed to oxygen. When you slice open an apple, the PPO reacts with the oxygen in the air and enzymatic browning occurs. That inhibits the enzyme that causes browning upon exposure to oxygen. When you cut the apple open, cells inside it are opened. Essentially your apple is rusting in a process called oxidation. posted by mathowie at 9:23 AM on October 23, 2006 . Why Are Ambrosia Apples so Slow to Brown? You open your lunch box to discover that the lovely apple you sliced this morning now appears unsightly and brown. Not very appetizing. Exposing those damaged cells to the air allows the oxygen to react with the iron and an enzyme called polyphenol oxidase, causing iron oxide to form. Apples are not the only fruits or vegetables that turn brown after being sliced because potatoes, bananas and a few others also exhibit the same color change. posted by mathowie at 9:23 AM on October 23, 2006 . The insides of apples turn brown when exposed to air thanks to a built in defense mechanism against bacteria and fungus. Pears, bananas, and eggplants also turn brown fairly quickly when cut. When you slice open an apple, the PPO reacts with the oxygen in the air and enzymatic browning occurs. The insides of apples turn brown when exposed to air thanks to a built in defense mechanism against bacteria and fungus. If the apples are sold pre-sliced, they have been dipped in a natural preservative such as ascorbic acid. Apples: Why Are Some Brown Inside (But look Good Outside) Have you bought apples (especially Fuji) that look great and when you get them how and cut them open, you find they are brown or have brown spots inside? It certainly doesn’t look or sound appealing—which begs the question, are brown apples safe to eat? What happens is that when the apple is cut, the cells are injured and thus the exposed portions of the cells come in full contact with the outside air. Why do apples turn brown and what can you do about it? Late, late follow up. Why Do Apples Turn Brown? On the other hand, using cutlery that has some corrosion (common with lower quality steel knives) can increase the rate and amount of the browning by making more iron salts available for the reaction. Have you ever wondered why apple slices turn brown when exposed to air? I thought it would help the process to first learn what makes apples turn brown in the first place. Subscribe here: http://goo.gl/B2RPd Watch SciTunes: http://goo.gl/fCSXF What do apples and cars have in common? The purpose of this chemistry laboratory exercise is to observe the effects of acids and bases on the rate of browning of apples when they are cut and the enzymes inside them are exposed to oxygen. We paired this with our Apple 5 Senses Activity. Enzymes in the fruit (like polyphenol oxidase) make this process go faster. Why Does Cilantro Taste Like Soap to Some People? This triggers an enzyme known as polyphenol oxidase (PPO) to—wait for it—oxidize polyphenols in the apple’s flesh. Let's try to answer these burning apple science questions with an apple oxidation experiment that is pretty quick and easy to set up at home or in the classroom. Grab some apples and have fun! Why Do Apples Turn Brown? Sep 10, 2014 - Learn why apples turn brown in this fun STEM experiment. Why Do Apples Turn Brown? 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